1. Visual neuroscience: Illuminating the dark corners
Michael A. Paradiso 
Current Biology 
Volume 10, Issue 1, Pages R15-R18 (January 2000)
DOI: /S (99)

2. Figure 1
Lightness illusions and their enhancement by illumination cues. (a) Lightness induction. The two gray squares have the same luminance, but the square surrounded by white appears darker than the square surrounded by black. (b) The Craik-O’Brien-Cornsweet effect. At the midline is a sharp transition from white on the left to black on the right. Luminance gradients extend from the midline into gray flanks. The flanks have the same luminance, but the one on the left appears slightly lighter. (c) An enhanced version of lightness induction. The diamond labeled 1 appears darker than the diamond labeled 2 though they actually have the same luminance. (d) An enhanced version of the Craik-O’Brien-Cornsweet effect. The object in the foreground has an edge at its center similar to that in (b). The top half of the object is perceived to be darker than the bottom. (Panel (c) courtesy Alexander Logvinenko; panel (d) courtesy Dale Purves).
Current Biology  , R15-R18DOI: ( /S (99) )